I couldn't figure out how to use the hdmi_timing mentioned in this thread, in order to get 2560x1080 (21:9) resolution on a Dell ultrawide monitor. I tried putting: hdmi_group=2 hdmi_mode=87 hdmi_timing=2560 0 0 0 0 1080 0 0 0 0 0 0 0 60 0 230000000 7 into config.txt, but the result was 640x480. Not...